Acipimox, a nicotinic acid analog, stimulates growth hormone secretion in short healthy prepubertal children

Recent studies in adult volunteers have demonstrated that the free fatty ac id reduction induced by acipimox, a nicotinic acid analog, stimulated GH se cretion per se and enhanced in an additive manner the GH secretion elicited by such different stimuli as pyridostigmine, GHRH and GHRP-6, In order to evaluate whether acipimox administration stimulates GH secretion in prepube rtal children, we administered a single oral dose pf acipimox (100 mg for c hildren weighing <30 kg and 200 mg for those >30 kg) to 14 healthy prepuber tal children with a mean age of 8.2 +/- 1.9 years, a mean bone age of 6.2 /- 3.0 years, growing along the 5-10(th) percentiles, and with normal thyro id function and IGF-I levels, Acipimox administration elicited a sustained increase in GH from a mean baseline level of 0.6 +/- 0.4 to 6.7 +/- 2.4 mug /l at the end of the test (p<0.05), with a mean GH peak of 10.5 +/- 3.5 <mu >g/l. GH release was delayed so that peak GH levels were achieved 180 minut es after acipimox administration. In order to determine whether acipimox wa s capable of enhancing the GH secretion elicited by levodopa (L-Dopa), we a dministered either oral L-Dopa (250 mg for children weighing <30 kg and 500 mg for those >30 kg) or oral acipimox plus L-Dopa to the same children on different days. GH concentrations increased in a similar fashion following either of these tests (from a baseline level of 1.2 +/- 0.4 and 0.7 +/- 0.4 mug/l to 8.4 +/- 2.7 and 9.3 +/- 2.9 mug/l at the end of the test (p<0.001 ), with peak GH concentrations of 13.1 +/- 4.1 and 11.8 +/- 3.3 <mu>g/l aft er L-Dopa or acipimox plus L-Dopa, respectively), Although the peak GH conc entrations obtained after the combined administration of acipimox plus L-Do pa were similar to those obtained after either acipimox or L-Dopa administr ation, a larger number of our patients reached a GH cut-off point of >7 mug /l following combined therapy than with either stimulus alone (13/14 patien ts with combined therapy and 10/14 with acipimox alone). No side effects ot her than mild facial flushing were noted after acipimox administration, The se results indicate that: 1) following the administration of a single oral dose of acipimox, significant GH secretion was elicited in healthy short pr epubertal children; 2) the combined administration of acipimox plus L-Dopa did not, however, enhance the GH secretion of this group of children; 3) ac ipimox was well tolerated with minimal side effects; and 4) further studies in both GH sufficient and GH deficient children are necessary to evaluate acipimox's usefulness in assessing GH reserve.